Systems that manage pressure within a well annulus of a sub-sea mineral extraction well are known. Some such systems provide a simple one-time pressure release, such as a rupture disc, for releasing pressure within the well great enough to damage the well. Other systems provide for more sophisticated release of fluid out of the well annulus. However, conventional system generally release excess fluid directly into the sea.
In conventional systems wherein provision has been made for communication (venting) to the sea, after a temperature increase has caused fluid to be released from the annulus, seawater is used to replace the fluid as the well cools. Systems with check valves that prevent seawater re-entry into the annulus when it cools are susceptible to well failure caused by the resultant confined annular pressure dropping too low and allowing implosion of one of the annular walls. Systems that do permit seawater to re-enter the annulus expose the casing strings to chloride and biologic corrosion.